Fix "Reload with full diff" URL button in compare branch view

This button worked when viewing merge requests because the JavaScript
stripped the .html in the Ajax request. However, it left the .html suffix
in the compare branch view.

CHANGELOG

@@ -3,6 +3,7 @@ Please view this file on the master branch, on stable branches it's out of date.
 v 7.14.1
   - Only include base URL in OmniAuth full_host parameter (Stan Hu)
   - Fix Error 500 in API when accessing a group that has an avatar (Stan Hu)
+  - Fix "Reload with full diff" URL button in compare branch view (Stan Hu)
 v 7.14.0
   - Fix bug where non-project members of the target project could set labels on new merge requests.

app/views/projects/diffs/_warning.html.haml

@@ -3,7 +3,7 @@
     Too many changes to show.
     .pull-right
       - unless diff_hard_limit_enabled?
-        = link_to "Reload with full diff", url_for(params.merge(force_show_diff: true, format: :html)), class: "btn btn-sm btn-warning"
+        = link_to "Reload with full diff", url_for(params.merge(force_show_diff: true, format: nil)), class: "btn btn-sm btn-warning"
       - if current_controller?(:commit) or current_controller?(:merge_requests)
         - if current_controller?(:commit)

features/project/commits/commits.feature

@@ -41,6 +41,7 @@ Feature: Project Commits
   Scenario: I browse big commit
     Given I visit big commit page
     Then I see big commit warning
+    And I see "Reload with full diff" link
   Scenario: I browse a commit with an image
     Given I visit a commit with an image that changed

features/steps/project/commits/commits.rb

@@ -79,6 +79,12 @@ class Spinach::Features::ProjectCommits < Spinach::FeatureSteps
     expect(page).to have_content "Too many changes"
   end
+  step 'I see "Reload with full diff" link' do
+    link = find_link('Reload with full diff')
+    expect(link[:href]).to end_with('?force_show_diff=true')
+    expect(link[:href]).not_to include('.html')
+  end
+
   step 'I visit a commit with an image that changed' do
     visit namespace_project_commit_path(@project.namespace, @project, sample_image_commit.id)
   end